Figure 2

Surface characterization. (a) The different structural elements (annotated as components C1–C5, with C1: C–H, C–C; C2: C–N, C=N, C≡N, C–O; C3: (N–)C=O, N–C–O; C4: O–C=O and C5: shake-up associated with unsaturated and/or aromatic hydrocarbon) that are present in AMN-based polymer coatings are reflected in the C 1s high resolution XPS spectrum obtained on a polystyrene (PS) substrate. (b) The XPS survey spectrum obtained on the same sample highlights the characteristic high nitrogen content of AMN coatings. (c, d) SEM images obtained on mica and polystyrene surfaces coated over 24 h using a 100 mM phosphate buffer suggest a substrate-dependent coating morphology. (d–f) SEM images obtained on polystyrene surfaces coated over 24 h using 100 mM phosphate buffer, 10 mM phosphate buffer and no buffer, respectively, suggesting a phosphate concentration-dependent coating morphology. AMN, aminomalononitrile; XPS, X-ray photoelectron spectroscopy.